Here’s what you need to know to make the home-buyer tax credit pay off for you.

Who Qualifies ...

Under the new rules, there are actually two credits:

First-time home buyers with adjusted gross incomes up to $125,000 (singles) or $225,000 (married) can get the full $8,000 tax credit if they purchase a primary residence before June 30, 2010 and haven’t owned a home in the past three years. The credit shrinks if your income is over those levels and is not allowed once income hits $145,000 for singles or $275,000 for married couples.

Current homeowners can snag a credit of up to $6,500 if they’ve lived in their primary residence for five concurrent years out of the past eight, meet the same income thresholds as first-time buyers, and purchase a primary residence before June 30, 2010.

... And Who Doesn’t

In addition to buyers who top out the income limits, there are a few other buyers who are excluded.

Luxury market: You can’t use the new tax credit to buy a property that costs $800,000 or more.

Vacation or investment homes: You can’t claim the credit to buy a second home, vacation residence, or investment property.

Also worth noting: You can’t take the credit if you acquired the home as a gift or inheritance or from your spouse, parents, grandparents, children, or grandchildren.

How Long Do You Have?

The new extension actually pushes the deadline back an additional seven months.Although the credit technically expires on April 30, 2010, if you have a binding contract by that date and close by June 30, you’ll still qualify. (The original credit was due to expire November 30, 2009.)

Members of the U.S. armed forces, military intelligence, or foreign service on qualified extended duty get an extra year to take either credit. And if you or your spouse has been deployed overseas for 90 days or more in 2008 or 2009, you have until April 30, 2011 to claim the tax credit.

When Do You Get the Credit?

Glad you asked: Buyers don’t actually have to wait to file their 2010 returns to get the credit. As long as you buy a home in 2010 before the program expires, you can claim the tax break on your 2009 federal tax return.

Is There a Catch?

The feds don’t want to be seen as helping house flippers, so if you take the credit, you will need to stay put. If you sell the home or move to a different primary residence within three years of closing, you’ll then be forced to repay the tax credit.

Advice for Buyers

If you’re married and never owned a home, but your spouse owned one within the past three years, the two of you won’t qualify for the $8,000 first-time home-buyer credit. You will qualify for the $6,500 credit for current homeowners, assuming you both meet the other requirements.

But if you want to buy a house with your child, the credit’s available even if you already own a primary residence. Your child will get the credit of up to $8,000 as long as he or she meets the other qualifications — even if you own half the property.

}

What If I’m Not in the Market?

Even if you’re not shopping for a home, the credit is likely to offer you a payoff.

Sellers: If your house is priced below $800,000, be sure to include language in your selling materials and online, reminding both first-time and trade-up buyers that your home may help them qualify for the credit.

Homeowners: Even if you’re not planning to buy another house soon, the credit could help your net worth. The first iteration of the credit certainly seemed to have an impact — the National Association of Realtors says first-time buyers accounted for more than 45 percent of home sales in the past year. If the new tax credit works as well, it could aid the sales of hundreds of thousands of additional homes, sopping up more of the excess inventory. And that’s exactly what you want to happen: Your home value can’t begin to rise until the other homes in your neighborhood are sold.

Ilyce R. Glink is an award-winning, nationally syndicated columnist, best-selling book author, and radio talk show host who also hosts "Expert Real Estate Tips," a Internet video show. She owns and operates several websites including ThinkGlink.com, ExpertRealEstateTips.net, LawProblems.com, and HouseTask.com, as well as Think Glink Publishing LLC, a privately held company that provides consulting services as well as editorial content and video for companies and non-profit organizations. An in-demand speaker, she appears frequently on CNN, CNBC, NPR, and in local media outlets across the country.